depends autoconf &&

optional_depends zlib \
                 "--enable-zlib" \
                 "--disable-zlib" \
                 "to decompress data before filtering" &&

optional_depends pcre                         \
                 '--enable-dynamic-pcre'      \
                 '--disable-dynamic-pcre'     \
                 'for PCRE (Perl regexp) support' &&

optional_depends docbook-dtd \
                 '--with-docbook=$INSTALL_ROOT/usr/share/sgml/docbook/xml-dtd-4.2' \
                 '--without-docbook' \
                 'generation of docs'
